The present invention relates to a high security seal of the padlock type and, more particularly, to a seal having a wire shackle that is first threaded through a structure to be secured and then locked in a seal body such that the seal must be broken to be opened. The present invention also relates to a method of making such seals.
Security seals of the padlock type are generally well known, and they have found wide spread use for sealing structures such as currency bags, closures, electric meters, and the like. Examples of such seals may be found in the following U.S. Patents: U.S. Pat. Nos. 3,485,461; 3,373,033; 3,980,332; 4,353,583; 4,278,281; and 4,687,240.
All of these seals have, generally, a plastic body with a pair of spaced cavities in which a U-shaped shackle is permanently locked. Locking the shackle is typically accomplished by a pair of reversely bent, resilient legs that register with a bump or depression located in the spaced cavities. Although such devices have served the purpose, they have not provided entirely satisfactory, because some efforts to defeat such structures by picking have proved successful. Those concerned with the development of such security seals have long recognized the need for providing such seals with improved anti-picking characteristics. For example, the above-cited U.S. Pat. No. 3,375,033 shows a special shackle having means specifically provided to discourage picking by making it difficult to insert a picking tool into the body cavity. However, even though such efforts have proved successful, some seal picking persists. One such method of picking involves inserting a picking tool into the seal body and deforming the shackle legs to an extent that the legs can freely be withdrawn from the seal body, reformed, and later replaced in the seal body.